The invention relates generally to a medical device, and more particularly to an auto-injector for injecting a medicament into a body of a patient.
Exposure to certain substances, such as, for example, peanuts, shellfish, bee venom, certain drugs, toxins, and the like, can cause allergic reactions in some individuals. Such allergic reactions can, at times, lead to anaphylactic shock, which can cause a sharp drop in blood pressure, hives, and/or severe airway constriction. Accordingly, responding rapidly to mitigate the effects from such exposures can prevent injury and/or death. For example, in certain situations, an injection of epinephrine (i.e., adrenaline) can provide substantial and/or complete relief from the allergic reaction. In other situations, for example, an injection of an antidote to a toxin can greatly reduce and/or eliminate the harm potentially caused by the exposure.
Because emergency medical facilities may not be available when an individual is suffering from an allergic reaction, some individuals carry an auto-injector to rapidly self-administer a medicament in response to an allergic reaction. Some known auto-injectors are cylindrical in shape and include a spring loaded needle to automatically penetrate the user's skin and inject the medicament. Such known auto-injectors can be bulky and conspicuous, which can make carrying them inconvenient and undesirable. Moreover, some known auto-injectors do not have a retractable needle and, as such, cause a sharps hazard when injection is complete.
Some known auto-injectors use pressurized gas to insert a needle and/or inject a medicament into the patient. Such known auto-injectors often do not include a mechanism for completely releasing or venting the pressurized gas upon completion of the injection event.
Thus, a need exists for an auto-injector that can be more conveniently carried by a user and does not present a sharps hazard upon completion of the injection. Furthermore, a need exists for a gas-powered auto-injector that has an improved gas release mechanism.